This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-305809, filed Oct. 5, 2000, No. 2001-057056, filed Mar. 1, 2001, No. 2001-057057, filed Mar. 1, 2001; and No. 2001-060565, filed Mar. 5, 2001, the entire contents of all of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a photovoltaic module and to the manufacturing method thereof, and in particular, to a photovoltaic module including hybrid-type photovoltaic cells each provided with a conductive interlayer having a light-transmitting-and-reflecting property, and to the manufacturing method thereof.
2. Description of the Related Art
The photovoltaic module generally has a structure in which a plurality of photovoltaic cells are arrayed in series on a glass substrate. These photovoltaic cells are respectively formed through the depositions on the glass substrate and patterning, of a transparent front electrode, a photovoltaic layer and a back electrode.
This photovoltaic module is demanded to be excellent in conversion efficiency of light to electric power (or power generating efficiency). A module including tandem-type photovoltaic cells, i.e. a tandem-type module has a structure in which a laminate structure of photovoltaic layers differing in absorption band of wavelength from each other intervenes between the front electrode and the back electrode, and is known to be capable of more effectively utilizing the incident light.
A hybrid-type structure which is one kind of tandem-type structure is featured in that the photovoltaic layers are different to each other in crystallinity of intrinsic semiconductor layer which constitutes a main portion of each photovoltaic layer. For example, a module having hybrid-type cells, i.e. a hybrid-type module employs, as the intrinsic semi-conductor layer of the photovoltaic layer disposed on the incident light side (or front side), an amorphous silicon layer having a wider band gap, and also employs, as the intrinsic semiconductor layer of the photovoltaic layer disposed on the rear side, a polysilicon layer having a narrower band gap.
By the way, there is a kind of tandem-type module wherein a conductive interlayer exhibiting a light-transmitting-and-reflecting properties is interposed between a plurality of photovoltaic layers being laminated. Since it is possible, with this interlayer being provided as mentioned above, to enable the light entered into the intrinsic semiconductor layer disposed on the front side to be reflected by this interlayer, the effective thickness of the intrinsic semiconductor layer disposed on the front side can be increased, or in other words, the density of output current of the photovoltaic layer disposed on the front side can be increased.
Therefore, if this interlayer is applied to the aforementioned hybrid-type cell, the density of output current may be well-balanced between the photovoltaic layer having an amorphous silicon layer and the photovoltaic layer having a polysilicon layer while making it possible to make thinner the amorphous silicon layer which may be increasingly photo-induced degraded as the thickness thereof is increased. Namely, the output performance of the module is assumed to be improved.
However, as a matter of fact, it is not necessarily possible, in the hybrid-type module which is provided with the aforementioned interlayer, to realize such an improved output performance as expected.
According to a first aspect of the present invention, there is provided a photovoltaic module including a transparent substrate and hybrid photovoltaic cells arrayed on the substrate and series connected to each other, the cells including a back electrode facing the substrate, a transparent front electrode intervening between the substrate and the back electrode, a first photovoltaic layer intervening between the front and back electrodes and including an amorphous semiconductor layer, a second photovoltaic layer intervening between the first photovoltaic layer and the back electrode and including a crystalline semiconductor layer, and a conductive interlayer with a light-transmitting-and-reflecting property intervening between the first and second photovoltaic layers and having a thickness in a range of 10 nm to 100 nm and a specific resistance in a range of 1xc3x9710xe2x88x923 xcexa9xc2x7cm to less than 1xc3x9710xe2x88x921 xcexa9xc2x7cm.
According to a second aspect of the present invention, there is provided a photovoltaic module including a transparent substrate and hybrid photovoltaic cells arrayed on the substrate and series connected to each other, the cells including a back electrode facing the substrate, a transparent front electrode intervening between the substrate and the back electrode, a first photovoltaic layer intervening between the front and back electrodes and including an amorphous semiconductor layer, a second photovoltaic layer intervening between the first photovoltaic layer and the back electrode and including a crystalline semiconductor layer, and a conductive interlayer with a light-transmitting-and-reflecting property intervening between the first and second photovoltaic layers, wherein, between a first cell and a second cell being adjacent to each other, the front electrode is divided by a first separation groove which is filled with a material of the first photovoltaic layer, a laminate structure including the first photovoltaic layer, the interlayer, the second photovoltaic layer and the back electrode is divided by a second separation groove which is apart from the first separation groove, a laminate structure including the first photovoltaic layer, the interlayer and the second photovoltaic layer is divided by a connection groove between the first and second separation grooves, the connection groove being filled with a material of the back electrode so as to electrically connect the back electrode of the first cell to the front electrode of the second cell, and a laminate structure including the first photovoltaic layer and the interlayer is divided by a third separation groove which is filled with a material of the second photovoltaic layer, the connection groove being positioned between the second and third grooves, and the first and third grooves being apart from each other.
According to a third aspect of the present invention, there is provided a photovoltaic module including a transparent substrate and hybrid photovoltaic cells arrayed on the substrate and series connected to each other, the cells including a back electrode facing the substrate, a transparent front electrode intervening between the substrate and the back electrode, a first photovoltaic layer intervening between the front and back electrodes and including an amorphous semiconductor layer, a second photovoltaic layer intervening between the first photovoltaic layer and the back electrode and including a crystalline semiconductor layer, and a conductive inter layer with a light-transmitting-and-reflecting property intervening between the first and second photovoltaic layers, wherein, between a first cell and a second cell being adjacent to each other, the front electrode is divided by first and fourth grooves which are apart from each other and filled with a material of the first photovoltaic layer, a laminate structure including the first photovoltaic layer, the interlayer, the second photovoltaic layer and the back electrode is divided by a second separation groove, the second and first separation grooves sandwiching the fourth groove, a laminate structure including the first photovoltaic layer, the interlayer and the second photovoltaic layer is divided by a connection groove between the fourth and second separation grooves, the connection groove being filled with a material of the back electrode so as to electrically connect the back electrode of the first cell to the front electrode of the second cell, and a laminate structure including the first photovoltaic layer and the interlayer is divided by a third separation groove which is filled with a material of the second photovoltaic layer and positioned between the first and fourth grooves, wherein a bottom surface of the third separation groove includes a surface of the transparent front electrode.
According to a fourth aspect of the present invention, there is provided a photovoltaic module including a transparent substrate and hybrid photovoltaic cells arrayed on the substrate and series connected to each other, the cells including a back electrode facing the substrate, a transparent front electrode intervening between the substrate and the back electrode, a first photovoltaic layer intervening between the front and back electrodes and including an amorphous semiconductor layer, a second photovoltaic layer intervening between the first photovoltaic layer and the back electrode and including a crystalline semiconductor layer, and a conductive interlayer with a light-transmitting-and-reflecting property intervening between the first and second photovoltaic layers, wherein, between a first cell and a second cell being adjacent to each other, the front electrode is divided by a first separation groove which is filled with a material of the first photovoltaic layer, a laminate structure including the first photovoltaic layer, the interlayer, the second photovoltaic layer and the back electrode is divided by a second separation groove which is apart from the first separation groove, a laminate structure including the first photovoltaic layer, the interlayer and the second photovoltaic layer is divided by a connection groove between the first and second separation grooves, the connection groove being filled with a material of the back electrode so as to electrically connect the back electrode of the first cell to the front electrode of the second cell, and a laminate structure including the front electrode, the first photovoltaic layer and the interlayer is divided by a third separation groove which is filled with a material of the second photovoltaic layer, the connection groove being positioned between the second and third grooves, and the first and third grooves being apart from each other.
According to a fifth aspect of the present invention, there is provided a photovoltaic module including a transparent substrate and hybrid photovoltaic cells arrayed on the substrate and series connected to each other, the cells including a back electrode facing the substrate, a transparent front electrode intervening between the substrate and the back electrode, a first photovoltaic layer intervening between the front and back electrodes and including an amorphous semiconductor layer, a second photovoltaic layer intervening between the first photovoltaic layer and the back electrode and including a crystalline semiconductor layer, and a conductive interlayer with a light-transmitting-and-reflecting property intervening between the first and second photovoltaic layers, wherein, between a first cell and a second cell being adjacent to each other, a laminate structure including the front electrode, the first photovoltaic layer and the interlayer is divided by a first separation groove which is filled with a material of the second photovoltaic layer, a laminate structure including the first photovoltaic layer, the interlayer, the second photovoltaic layer and the back electrode is divided by a second separation groove which is apart from the first separation groove, and a laminate structure including the first photovoltaic layer, the interlayer and the second photovoltaic layer is divided by a connection groove between the first and second separation grooves, the connection groove bordering on the first separation groove and being filled with a material of the back electrode so as to electrically connect the back electrode of the first cell to the front electrode of the second cell. The material filling the connection groove and the material filling the first separation groove are in direct contact with each other and a contact surface of the material filling the connection groove that is in direct contact with the material filling the first separation groove extends from a back surface of the front electrode to a front surface of the back electrode.
The term xe2x80x9ccrystallinexe2x80x9d employed herein is to be interpreted inclusively and is meant to include xe2x80x9cpolycrystallinexe2x80x9d and also xe2x80x9cmicrocrystallinexe2x80x9d. Further, these xe2x80x9cpolycrystallinexe2x80x9d and xe2x80x9cmicrocrystallinexe2x80x9d may contain therein an xe2x80x9camorphousxe2x80x9d.
Additional advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.